Epidemiological characteristics of imported severe malaria cases in Zhejiang Province from 2012—2020

doi:10.12140/j.issn.1000-7423.2021.04.008

Abstract

Abstract:

Objective To understand the epidemiological characteristics and influencing factors of imported severe malaria cases in Zhejiang Province. Methods The epidemiological data of imported severe malaria cases in Zhejiang Province from 2012 to 2020 were collected. SPSS 20.0 software was used to analyze the species of Plasmodium, distribution of cases, countries source of infection, interval time from disease onset to diagnosis were analyzed. Multivariate logistic regression analysis was conducted to analyze factors affecting severe malaria. Results A total of 127 severe malaria cases were reported in Zhejiang Province from 2012 to 2020, all were imported from abroad. Of them, 107 were infected with Plasmodium falciparum (84.25%), 11 with P. vivax (8.66%), 7 with P. ovale (5.51%), and 2 with mixed infection (1.57%). The severe malaria cases were distributed in 11 cities of Zhejiang Province, with the top 3 cities with the percentage to total reported cases being Taizhou (17.65%, 24/136), Ningbo (13.45%, 16/119) and Wenzhou (11.64%, 22/189). The number of severe cases in January, October and December accounted for more than 10% of the total reported cases, respectively. Among the 127 cases, 116 were males and 11 were females, and the mala/female ratio was 10.55 : 1, mainly occurred in the age of 30-59 years (98 cases, 77.17%), and among workers and businessmen. There were 9 foreigner cases, and 2 deaths occurred in 2013 and 2016. The source place of infection showed that 93.70% of the severe cases were imported from African countries, with top countries of Nigeria (35, 27.56%), Equatorial Guinea (13, 10.24%) and Democratic Republic of Congo (11, 8.66%). The time interval from initial diagnosis to diagnosis of severe malaria was longer than that of non-severe malaria cases (Z = -3.285, P < 0.05). Age (OR = 1.022, 95%CI: 1.004-1.041) and the time interval from initial diagnosis to diagnosis (OR = 1.046, 95%CI: 1.004-1.089) were the risk factors for severe disease. Foreign nationality (OR = 0.488, 95%CI: 0.241-0.990) and previous history of malaria (OR = 0.598, 95%CI: 0.399-0.895) had less chance causing severe malaria. Conclusion Imported severe malaria cases in Zhejiang Province are distributed in Hangzhou, Taizhou, Wenzhou and other cities. Most of them are males, aged 30-59 years, among workers and businessmen. The severe cases were mainly imported from Africa. Age and the time interval between first diagnosis and diagnosis are risk factors leading to severe malaria.

Key words: Severe case, Imported malaria, Epidemiological characteristics, Influencing factors

CLC Number:

R531.3

ZHANG Xuan, RUAN Wei, WANG Xiao-xiao, CHEN Hua-liang, LU Qiao-yi, ZHANG Jia-qi, YU Ke-gen, YAO Li-nong. Epidemiological characteristics of imported severe malaria cases in Zhejiang Province from 2012—2020[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2021, 39(4): 466-472.

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变量Variable	赋值Assignment
年龄Age	连续变量Continuous data
国籍Nationality	中国籍Chinese = 0;外籍Foreigners = 1
病种Species	恶性疟Falciparum malaria = 0;非恶性疟Non-falciparum malaria = 1
疟疾患病史 Previous history of malaria	无No = 0;有Yes = 1
初诊到确诊间隔/d Time from initial diagnosis to diagnosis/d	连续变量Continuous data

国家 Country	恶性疟 P. falciparum	间日疟 P. vivax	卵形疟 P. ovale	混合感染 Mixed infection	合计 Total
非洲 Africa
尼日利亚 Nigeria	31	0	4	0	35
赤道几内亚 Equatorial Guinea	8	3	1	1	13
刚果(金) Democratic Republic of Congo	10	0	1	0	11
安哥拉 Angola	7	0	0	0	7
加纳 Ghana	6	0	0	0	6
加蓬 Gabon	5	0	0	0	5
塞拉利昂 Sierra Leone	4	0	1	0	5
几内亚 Guinea	4	0	0	0	4
喀麦隆 Cameroon	4	0	0	0	4
科特迪瓦 Cote d'lvoire	3	0	0	0	3
南非 South Africa	3	0	0	0	3
贝宁 Benin	3	0	0	0	3
刚果布Republic of Congo	3	0	0	0	3
马拉维 Malawi	3	0	0	0	3
莫桑比克 Mozambique	3	0	0	0	3
埃塞俄比亚 Ethiopia	0	1	0	1	2
坦桑尼亚 Tanzania	2	0	0	0	2
乌干达 Uganda	2	0	0	0	2
赞比亚 Zambia	2	0	0	0	2
苏丹 Sudan	0	1	0	0	1
南苏丹 South Sudan	1	0	0	0	1
塞内加尔 Senegal	1	0	0	0	1
亚洲 Asia
巴基斯坦 Pakistan	0	3	0	0	3
缅甸 Burma	1	1	0	0	2
老挝 Laos	1	0	0	0	1
大洋洲 Oceania
巴布亚新几内亚 Papua New Guinea	0	1	0	0	1
所罗门 Solomon	0	1	0	0	1
合计 Total	107	11	7	2	127

因素 Variable	重症疟疾病例 Severe malaria cases	非重症疟疾病例 Non-severe malaria cases	χ²值/Z值 χ² value/Z value	P值 P value
性别 Gender			0.309	> 0.05
男 Male	116	1 319
女 Female	11	150
年龄 Age			-2.204	< 0.05
中位数（四分位间距） Median (P₂₅, P₇₅)	43(32,50)	40(31,48)
职业 Occupation			4.155	> 0.05
务工 Worker	76	843
经商 Business services	38	457
公务 Public affairs	5	27
其他 Others	8	142
国籍 Nationality			6.576	< 0.01
中国 Chinese	118	1 241
外籍 Foreigners	9	228
分型 Species			4.674	< 0.05
恶性疟Falciparum malaria	107	1 113
非恶性疟Non-falciparum malaria
间日疟Vivax malaria	11	168
卵形疟Ovale malaria	7	146
混合感染Mixed infection	2	11
三日疟Quartan malaria	0	31
发病地点在国外Illness onset abroad			3.097	> 0.05
是 Yes	21	166
否 No	106	1 303
疟疾患病史Previous history of malaria			6.646	< 0.01
有 Yes	56	822
无 No	71	647
初诊机构属性 Administrative level of initial diagnosis institution			0.624	> 0.05
县级及以下 County level or lower	78	938
市级 City level	36	370
省级 Province level	13	161
确诊机构属性 Administrative level of diagnosis institution			5.385	> 0.05
县级及以下 County level or lower	54	775
市级 City level	51	509
省级 Province level	22	185
时间间隔（四分位间距） Time interval (P₂₅, P₇₅)
发病到初诊间隔Illness-initial diagnosis	1(0,3)	1(0,3)	-0.548	> 0.05
初诊到确诊间隔Initial diagnosis-diagnosis	1.5(0,3)	1(0,2)	-3.285	< 0.01

变量Variable	回归系数β Regression coefficient β	标准误SE	Wald χ²值 Wald χ² value	P值 P value	OR值 OR value	95%CI
年龄 Age	0.022	0.009	5.476	< 0.05	1.022	1.004~1.041
国籍Nationality	-0.717	0.360	3.955	< 0.05	0.488	0.241~0.990
分型Species	-0.369	0.277	1.770	> 0.05	0.691	0.401~1.191
疟疾患病史Previous history of malaria	-0.515	0.206	6.227	< 0.05	0.598	0.399~0.895
初诊到确诊时间间隔Time from initial diagnosis to diagnosis	0.045	0.021	4.551	< 0.05	1.046	1.004~1.089